Commit d1402fc7 authored by Logan Gunthorpe's avatar Logan Gunthorpe Committed by Linus Torvalds
Browse files

mm: introduce common STRUCT_PAGE_MAX_SHIFT define 

This define is used by arm64 to calculate the size of the vmemmap
region.  It is defined as the log2 of the upper bound on the size of a
struct page.

We move it into mm_types.h so it can be defined properly instead of set
and checked with a build bug.  This also allows us to use the same
define for riscv.

Link: http://lkml.kernel.org/r/20181107205433.3875-2-logang@deltatee.com


Signed-off-by: default avatarLogan Gunthorpe <logang@deltatee.com>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Acked-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Acked-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5b526090

arch/arm64/include/asm/memory.h

+0 −9
Original line number Diff line number Diff line
@@ -34,15 +34,6 @@ 
 */

#define PCI_IO_SIZE		SZ_16M



/*

 * Log2 of the upper bound of the size of a struct page. Used for sizing

 * the vmemmap region only, does not affect actual memory footprint.

 * We don't use sizeof(struct page) directly since taking its size here

 * requires its definition to be available at this point in the inclusion

 * chain, and it may not be a power of 2 in the first place.

 */

#define STRUCT_PAGE_MAX_SHIFT	6



/*

 * VMEMMAP_SIZE - allows the whole linear region to be covered by

 *                a struct page array

arch/arm64/mm/init.c

+0 −8
Original line number Diff line number Diff line
@@ -610,14 +610,6 @@ void __init mem_init(void) 
	BUILD_BUG_ON(TASK_SIZE_32			> TASK_SIZE_64);

#endif



#ifdef CONFIG_SPARSEMEM_VMEMMAP

	/*

	 * Make sure we chose the upper bound of sizeof(struct page)

	 * correctly when sizing the VMEMMAP array.

	 */

	BUILD_BUG_ON(sizeof(struct page) > (1 << STRUCT_PAGE_MAX_SHIFT));

#endif



	if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) {

		extern int sysctl_overcommit_memory;

		/*

include/asm-generic/fixmap.h

+1 −0
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#define __ASM_GENERIC_FIXMAP_H



#include <linux/bug.h>

#include <linux/mm_types.h>



#define __fix_to_virt(x)	(FIXADDR_TOP - ((x) << PAGE_SHIFT))

#define __virt_to_fix(x)	((FIXADDR_TOP - ((x)&PAGE_MASK)) >> PAGE_SHIFT)

include/linux/mm_types.h

+5 −0
Original line number Diff line number Diff line
@@ -206,6 +206,11 @@ struct page { 
#endif

} _struct_page_alignment;



/*

 * Used for sizing the vmemmap region on some architectures

 */

#define STRUCT_PAGE_MAX_SHIFT	(order_base_2(sizeof(struct page)))



#define PAGE_FRAG_CACHE_MAX_SIZE	__ALIGN_MASK(32768, ~PAGE_MASK)

#define PAGE_FRAG_CACHE_MAX_ORDER	get_order(PAGE_FRAG_CACHE_MAX_SIZE)

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